Cross-head attachment eor working steam-engine valves



UNITED STATES PATENT OFFICE.

JOHN B. STOTT AND ALEXANDER FERGUSON, OF TROY, NE\V YORK.

CROSS-HEAD ATTACHMENT FOR WORKING STEAM-ENGINE VALVES.

Specification of Letters Patent No. 13,276, dated July 17, 1855.

To all whom it may concern:

Be it known that we, .IoniT B. S'ror'r and ALEXANDER FERGUSON, of thecity of Troy, State of New York, have invented a new Method of Operatingthe Valves of the C-ylinders of Steam-Engines, which we call Stott andFergusons Cross-Head Atttachment Valve-Cam; and we dec-lare thefollowing specification, with the drawings attached hereto as part ofthe same, to be a full and perfect description thereof.

Figure l represents in perspective a view of the upper part of a steamcylinder with the apparatus for operating the valves attached, and witha portion of the upper valve chamber removed in order to afford a viewof the working of the valve. Figs. 2, 3, 4, 5, 6, 7 are diagrams showingthe various positions of valves as produced by the consecutive actionsof the operating apparatus. Fig. 8 is a. plan view of the crossheadattachment. Figs. 9 and 10 a plan (reversed) and profile of the cam.

Similar letters in the figures denote the same parts of the apparatus.

In Fig, l A represents the steam valve next the cylinder head. It is ahollow piston closed tight at the end toward the center of the cylinder.It moves within a hollow cylindrical casing to which it is fittedsteamtight by metallic rings or otherwise (being what is usually knownas a piston valve). It has slots cut around through its shell to afforda communication between its interior and the port B which communicateswith the eduction channels C C, the conimunicatian with the steam port Dbeing through its open end as shown in the drawing. This valve has (asusual) its counterpart within valve box E to make the communication withthe steam and eduction ports at the lower end of the cylinder, the twovalves being connected by a st-em G (which passes when the valves are inseparate chests through a pipe connecting them) the steam from theboiler being introduced either through this pipe, or into one of thevalve chests.

The stem G is prolonged through a stuffing box, and extended to connectwith the apparatus which operates the valves; and

which apparatus is arranged as follows: A`

lever or arm H passes at its outer end into a loop on the end of thestem Gr, or is linked to it in any of the usual methods of attachment.Its inner end is pinned to a vertical shaft J, supported properly by aframing, asV

shown in the drawing, upon or over one of the cross-head-slides L. Tothe lower end of this shaft a double-arm K is secured so as to traversejust above the slide L. At each end of the arm K is a stop or cam M1,M2, hanging therefrom, of peculiar form 'as shown on Fig. 9 (which is asketch of M1 turned over on its back, and Fig. 10 which is a sectionalproile,) having an oblique face to press against a corresponding face ona sliding trip which is to operate it, and a projecting lip to pass itover an inclined plane of the same trip. The stop M is attached to thearln K by a vertical spindle which passes up through it, into a box P, Fig. 10, within a spiral spring which keeps the stop habitually down asmall distance below the arm.

The operating apparatus is attached to the end of the cross-head R so asto slide forward and backward along or upon the frame or slide L, to theextent of the stroke of the piston of the engine. It consists of anirregularly shaped box W as shown in perspective in Fig. 1 and in planin Fig. 8. Its center is square, its extremities S and T tapering bothon the top and on the inner side, and it has a double tapering or curvedrecess V on the inner'side of its central part. )Vithin this box lyingin line with each other and parallel with the movement of the piston,are two square bars X X, whose outer ends are made tapering verticallyfrom their outer angles inwardly. These bars are connected together by aright and left threaded screw passing or tapped through their rear ends,said screw being operated by a thumb screw Y working an instep screwwheel (or analogous device) by turning which the bars can be projectedfrom or drawn near to each other.

The operation of the apparatus is thus: The position of the valve A andthe arm K being as shown in Fig. 1, and the steam admitted through thesteampipe Z, it enters the steamchests behind the valves, and passesdown, through the valve in chest E, which is wide open (as will beunderstood by examining the diagrams illustrating the next motions ofthe valves) and through the steamport into the cylinder below thepiston, while at the same time the steam above the piston passes upthrough the interior of the valve A and down through the wide open portB (as shown by the arrows) into the eduction channel C. Consequently thepiston with its cross-head moves up until the inclined end of bar Xreaches the stop or cam M1 which it presses aside, moving the arm K,shaft J, lever H and rod G, a little from right to left, shifting thevalve so as to place it as in diagram 2 closing the steam passage by thelower valve E and nearly closing the eduction passage by the valve A.The continued expansion of steam and momentum of piston continue itsmotion until the edge of T touches M which it moves a little fart-herback carrying the valves to the position shown in diagram 3 when theeduction passage is closed by valve A and the steam passage of the samevalve slightly opened, at the same time the eduction passage at theother or lower end of the cylinder is partially opened by valve E. Thisoccurs just as the piston arrives at the end of the up stroke. At thesame time that the vertical face of M1 presses against the face of T,the projecting lip overlying the upper oblique surface of T slides overit raising N l vertically against its spiral spring until it reaches therecess V when it drops into it just at the close of the pistons stroke.The movement of the piston becomes now reversed from top to bottom ofthe cylinder, and as it progresses, the right hand oblique edge of therecess V presses the lip of the cam outward through K one move fartherback to the position shown in diagram 4 opening wide the steam passagein valve E and the eduction passage in valve E giving full effect to thesteam. It will be seen that the valves are now in the posit-ion of thedownward stroke, relatively, that they were to the upward stroke in Fig.l, and that as the left hand bar X with the other apparatus of W operateagainst the cam l 2 a series of operations corresponding with those justdescribed will take place in reference to the downward stroke of theengine, and duly shift it to a second upward stroke.

The function of the bars X being to cut 0E the steam before thetermination of the stroke, and it being desirable, under varyingcircumstances of pressure of steam, rapidity of movement, on theeconomical use of expansive steam, to vary the point of cut off, theadvantage of the arrangement to vary the distance between theextremities of the bars X will be understood and the simple means bywhich it can be done by the turning of the thumb screw Y.

Figs. 5, 6, 7, show another and simpler division of the valves, inreference to the arrangement of steam ports, and giving better openingsthan those described7 but their operation is precisely the same withthose of 2, 3, 4, as will be seen by comparing the diagrams.

We claim- The method of operating the valves of steam cylinders by theprocess described in the above specification, to wit, by a series oftrips attached to and sliding with the cross head of the piston, whichtrips operate in succession upon the arms of a vibrating shaft connectedwiththe valve rod, through cams fixed near the ends of the arms; thetrips themselves consisting of a variable and adjustable one to move thevalves so as to cut oft7 the steam before the end of the pistons stroke,leaving the eduction passage slightly open ;y a second to shift thevalves a little farther at the end of the stroke so as to take steam forthe new stroke, and open wider the eduction passage, and a third toshift the valves so as to open the induction and eduction passages totheir fullest eX- tent; the two first movements of the valves being madeby the movement of the crosshead in one direction, and the other by thereverse movement thereof, the last operation being produced by the jointaction of the spring-cam on the arm K and the recessed trip Vsubstantially as set forth herein.

JOHN B. STOTT. ALEXANDER FERGUSON.

Witnesses RUTH VARCEK DE Wrr'r, W. C. MILLER,

